Acidic-Thermal Ageing Effect on Compression Stress Relaxation of Silicone Rubber

The compression properties of silicone rubbers used as gaskets in PEM fuel cells are studied. The specimens are aged under different test conditions, viz, high temperature, humid air, and acidic solutions, prepared to match real PEM fuel cell operation conditions. The compression and stress relaxation tests are conducted. Temperature, humid air and acidic solution exert a serious effects on the mechanical performance of silicone rubbers. All the three factors can cause an increase in the stress relaxation modulus and permanent compression deformation. The effects of high temperature and an acidic solution are more pronounced. This can accelerate the deterioration of mechanical properties and decrease the sealing efficiency of gaskets, which would influence the durability of PEM fuel cells. It creates the basis for life prediction of silicone rubbers under appropriate accelerated durability test conditions.